Automotive exterior panel

ABSTRACT

The present invention relates to a blow molded article with a smooth appearance and to the method of making the article. More particularly, the blow molding system of the present invention utilizes a thermal cycle to eliminate certain molding defects and a non-mirrored mold cavity surface to eliminate other molding defects. The thermal cycle sets the cavity temperature to a prescribed range to eliminate spot marks and line marks. The mold cavity surface has minute concavities/convexities and thereby produces an article with minute concavities/convexities such that when the article is painted, a smooth surface is produced without the need for sanding either the mold surface or the paint surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application which claims priority under 35 U.S.C. §120 to application U.S. application Ser. No. 09/344,801, filed on Jun. 25, 1999 now U.S. Pat No. 6,458,312, and priority under 35 U.S.C. §119 to Japanese Patent Applications No. 10-199665 filed on Jun. 30, 1998, and No. 10-236485 filed on Aug. 7, 1998, which are incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

The present invention relates to an automotive exterior panel having a good appearance and smooth finish and to a method for producing the panel.

Conventional methods for producing hollow molded articles having a smooth appearance disclose a method comprising disposing a parison, which is composed of a noncrystalline resin exhibiting a tensile modulus of 2000 Kg/cm² or more at 75° C., between mold halves having mirror-finished cavity surface, closing the mold and closely adhering the parison to the cavity by blowing a pressurizing air into the parison, wherein the parison is adhered to the cavity which is set to a cavity temperature Y° C. falling in the following range:

Y° C.=(0.96 X ₀−37) to (0.96 X ₀+3)

where X₀ is a temperature at which the tensile modulus of the noncrystalline resin is 2000 Kg/cm² (Japanese Patent Application Publication (JP-B) No. 6-22875).

With this method it is impossible to avoid the formation of spot marks or line marks on the external surface of the hollow article of noncrystalline resin. Therefore, when producing an automotive exterior panel whose appearance needs to meet strict requirements, the spot marks and the line marks need to be removed by polishing or wet-sanding the external surface of the blow-molded hollow article of noncrystalline resin prior to the painting of the external surface. Consequently, the number of process steps increases and production costs become higher.

Another prior art method for thermoforming or blow molding a thermoplastic resin, is described in (JP-B No. 1-27849), wherein the gloss of the surface of the molded article is increased by heating selectively and instantly the mold surface to a temperature higher than the thermal deformation temperature of the resin by means of high frequency induction heating.

This method suffers has significant drawback, because it is necessary to use a special molding apparatus equipped with a mold heating device designed for the high frequency induction-heating. Consequently, the production costs become higher.

In (JP-B No. 2-40498), a method comprising blow-molding a molten parison, which has on the surface thereof many minute concavities/convexities having a depth in the range of from 2 to 100 μm, by means of a mold which is heated to a temperature higher than the crystallization temperature of the resin and the surface of which is mirror-finished to a roughness of 0.5 μm or less.

The melt fracture is generated on the parison surface so as to create many minute concavities/convexities having a depth in the range of from 2 to 100 μm. The depth of the minute concavities/convexities are difficult to control, and the resulting article has a certain amount of surface roughness even after painting. However, the control of the melt fracture is difficult and therefore is not suited for mass production.

What is needed is an article that can be produced efficiently and in mass production that has a smooth appearance once painted, suitable for an automobile exterior panel. The process used to create such a panel should eliminate line marks, spot marks, and air marks. The process should allow for mass production and produce a cost-effective product.

SUMMARY OF THE INVENTION

The present invention has been achieved in view of the above-described problems of conventional technologies. It therefore is an object of the present invention to provide an automotive exterior panel which has excellent mechanical strengths, such as rigidity, and which presents a good appearance, free of coating imperfections such as orange peel, and allow painting without prior polishing or wet-sanding of the external surface of the blow molded hollow article.

Another object of the present invention is to provide a method for producing an automotive exterior panel.

In order to achieve the object, the first automotive exterior panel according to the present invention is an automotive exterior panel which is a blow molded article of a noncrystalline resin exhibiting a tensile modulus of 2000 Kg/cm² or more at 75° C. and which is coated with a 15 to 150 μm thick paint film, wherein the panel to be coated has surface irregularities comprising a surface roughness in the range of from 0.9 to 9.0 μm and an average peak-to-peak distance in the range of from 10 to 150 μm.

In order to achieve the object, the second automotive exterior panel according to the present invention is an automotive exterior panel which is a blow molded article of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C. and which is coated with a 15 to 150 μm thick paint film, wherein the panel to be coated has surface irregularities comprising a surface roughness in the range of from 0.9 to 9.0 μm and an average peak-to-peak distance in the range of from 10 to 150 μm.

Further, in the second automotive exterior panel, the crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C. may be incorporated with 3% to 35% by weight of an inorganic filler.

Still further, in the second automotive exterior panel, the crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C. is preferably polypropylene.

The first method of the present invention for producing the automotive exterior panel comprises the steps of producing a hollow molded article for automotive exterior panel by blow molding and painting the external face of the hollow molded article for automotive exterior panel, wherein a parison, which is composed of a noncrystalline resin exhibiting a tensile modulus of 2000 Kg/cm² or more at 75° C., is disposed between mold halves having minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm; the mold is then closed; and thereafter the parison is closely adhered by introducing thereinto a pressurized air to the cavity whose surface temperature is set to Y° C. which falls in the following range:

Y=(0.96X+3) to (0.96X+40)

where X is a temperature at which the tensile modulus of the noncrystalline resin is 2000 Kg/cm².

In the first method of the present invention for producing the automotive exterior panel, it is effective to set the cavity surface temperature Z° C., at which a mold opening process is completed for taking out the molded article for automotive exterior panel, to a temperature in the range of Z≦0.9X where X is a temperature at which the tensile modulus of the noncrystalline resin is 2000 Kg/cm².

For clarity and understandability, the variables used for the noncrystalline resin are capital ‘Y’ and capital ‘Z’, while the variables used for the crystalline resin are lower case ‘y’ and lower case ‘z’.

The second method of the present invention for producing the automotive exterior panel comprises the steps of producing a blow molded article for automotive exterior panel by blow molding and coating the external face of the molded article for automotive exterior panel with a 15 to 150 μm thick paint film, wherein a parison, which is composed of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C., is disposed between mold halves having minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm; the mold is then closed; and thereafter the parison is closely adhered by introducing therein a pressurized air to the cavity whose surface temperature is raised during the adhesion to y ° C. which falls in the following range:

A<y<1.07B

where A is a peak crystallization temperature (° C.) in a Differential Scanning Calorimetry (DSC) curve of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.; and B is a peak fusion temperature (° C.) in a DSC curve of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.

The third method of the present invention for producing the automotive exterior panel comprises the steps of producing a blow molded article for automotive exterior panel by blow molding and coating the external face of the molded article for automotive exterior panel with a 15 to 150 μm thick paint film, wherein a parison, which is composed of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C., is disposed between mold halves having minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm; a mold closing process is then started while raising the cavity surface temperature so as to reach a temperature y ° C. falling in the following range at a stage immediately before the closure of the mold:

A<y<1.07B

where A is a peak crystallization temperature (° C.) in a DSC curve of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C. while B is a peak fusion temperature (° C.) in a DSC curve of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.; the mold is then completely closed; and thereafter the parison is closely adhered to the cavity by introducing a pressurized air into the parison.

In the second method and in the third method of the present invention for producing the automotive exterior panel, it is effective to incorporate 3% to 35% by weight of an inorganic filler into the crystalline resin that exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.

Further, in the second method and in the third method of the present invention for producing the automotive exterior panel, it is effective to choose a temperature in the range of z≦A−15 for the cavity surface temperature (z° C.) at which a mold opening process is started for taking out the molded article for automotive exterior panel.

Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only a preferred embodiment of the invention is described, simply by way of illustration of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:

FIG. 1(a) is a diagrammatic cross-sectional view illustrating the state where a parison is extruded into the space between opened mold halves.

FIG. 1(b) is an exploded view of the surface of the parison, showing the rough surface.

FIG. 2(a) is a diagrammatic cross-sectional view illustrating the state where mold is opened after a blow-molded article is produced

FIG. 2(b) is an exploded view of the cavity surface, showing the smooth surface.

FIG. 3 is a view showing the prior art irregular surface after painting.

FIG. 4 is a diagrammatic cross-sectional view illustrating the state where a parison is extruded into the space between opened mold halves.

FIG. 5(a) is a diagrammatic cross-sectional view illustrating the state where a parison is extruded into the space between opened mold halves.

FIG. 5(b) is an exploded view of the surface of the cavities, showing the concavities/convexities.

FIG. 6 is a view showing the smooth outer surface after painting.

FIG. 7 is an oblique view illustrating a blow-molded article for a spoiler.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Spot marks and the line marks are created on the external face of blow molded hollow articles of resin according to the conventional prior art technologies, and are known to be caused by rough surface, die lines, and granular structures created on the external face of the parison.

The rough surface is caused by the flow of fused resin passing through the extrusion head when the parison is extruded and the rough surface is made up of irregular concave and convex portions having a height of about 2 μm or greater.

The die line is caused by the junction of fused resin in the direction of flow thereof in the extrusion head when the parison is extruded and the die line is a streaky dent having a depth in the range of from 2 to 500 μm.

The granular structure is caused by an unmelted particle or carbide of resin and the granular structure is a 2 to 1000 μm protrusion or dent on the external face of parison.

After extensive experimentation, the present inventors have found that the formation of spot marks and line marks, which appear on the external face of the molded article due to the presence of rough surface, die lines and granular structures on the external face of the parison, can be prevented by blow molding by the use of a mold having minute concavities/convexities comprising a specific surface roughness and average peak-to-peak distance and by carrying out the blow molding at a cavity surface temperature set to a specific temperature, instead of using a mold having a mirror-finished cavity surface.

This finding is a surprising fact from the standpoint of traditional knowledge, and this finding is important from two aspects. One aspect is that the problem of spot marks and line marks, which appear on the external face of the blow molded article due to the presence of rough surface, die lines and granular structures on the external face of the parison, can be eliminated by setting the cavity surface temperature to a specific temperature. The defects, such as spot marks and line marks, which are created on the parison surface when the parison is extruded, can be eliminated by raising the surface temperature of the parison to a specific temperature. In other words, because of the cavity surface temperature, the parison undergoes a kind of thermal treatment. As a result, the defects, such as spot marks and line marks, which cannot be eliminated by conventional technologies, can be eliminated as describe above. The thermal treatment can be analogized to ironing, wherein the heat takes wrinkles out of clothing.

Indeed, the defects, such as spot marks and line marks, which are created on the parison surface due to the presence of rough surface, die lines and granular structures on the external face of the parison, can be eliminated by a treatment which comprises raising the cavity surface temperature to a specific temperature. However, it has become clear that this treatment causes a crater-like defect, which is called an air mark, on the surface of the blow molded article. If the blow-molded article is painted without removing the air mark, the air mark is reflected to the paint film surface. Therefore, it is necessary to remove the air mark by polishing or wet-sanding prior to the application of paint, as hitherto practiced. In addition, it has become clear that the air marks are more concentrated on complicated portions of the blow molded article as the shape of the blow molded article becomes complicated. So while thermal treatment can eliminate spot marks and line marks, the air marks create a defective article.

It was revealed through research, that the formation of minute concavities/convexities on the cavity surface, in such a manner that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm, prevents the formation of the air mark. And, it provides excellent surface results which make the polishing or wet-sanding unnecessary. This is true even if the surface roughness of the cavity is greater than the surface roughness of the parison. Specific minute concavities/convexities, particularly those whose average peak-to-peak distance is in the range of from 10 to 150 μm, have a beneficial effect on paint film. This is because, when the blow molded article is painted, the paint penetrates into the minute concavities/convexities by a uniform capillary action and thus provides a defect-free smooth painted surface. According to the measurement conducted by the present inventors, the surface roughness of the parison after extrusion thereof was 3 μm and the average peak-to-peak distance was 539 μm. If the parison surface, whose average peak-to-peak distance is large despite the fairly small surface roughness, is not treated and is then painted, paint film defects such as orange peel emerge due to the emergence of the irregularities on the paint film because the peaks and valleys on the surface of the blow molded article cannot be fully covered and filled with the paint film.

Thus, the combination of the thermal treatment in conjunction with the prescribed surface roughness of the mold cavity eliminates the line marks, spot marks, and air marks and produce a quality appearance.

The present invention has been achieved based on the finding that the formation of spot marks and line marks, which appear on the external face of the blow molded article due to the presence of rough surface, die lines and annular structures on the external face of the parison, can be prevented by blow molding by the use of a mold having minute concavities/convexities comprising a specific surface roughness and average peak-to-peak distance and by carrying out the blow molding at cavity surface temperature set to a specific temperature, instead of using a mold having a mirror-finished cavity surface.

Accordingly, it has become clear that a beautiful paint film free of defects, such as orange peel, can be obtained if the substrate automotive exterior panel is an automotive exterior panel which is a hollow blow molded article of a noncrystalline resin exhibiting a tensile modulus of 2000 Kg/cm² or more at 75° C. and which is coated with a 15 to 150 μm thick paint film, wherein the substrate surface to be coated has specific irregularities comprising a surface roughness in the range of from 0.9 to 9.0 μm and an average peak-to-peak distance in the range of from 10 to 150 μm.

Further, it has become clear that a beautiful paint film free of defects, such as orange peel, can be obtained if the substrate automotive exterior panel is an automotive exterior panel which is a hollow blow molded article of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C. and which is coated with a 15 to 150 μm thick paint film, wherein the substrate surface to be coated has specific irregularities comprising a surface roughness in the range of from 0.9 to 9.0 μm and an average peak-to-peak distance in the range of from 10 to 150 μm. In addition, this automotive exterior panel was found to have the mechanical strengths, such as rigidity, which meet the requirement for automotive exterior panels.

In this case, if the crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C. is incorporated with 3% to 35% by weight of an inorganic filler, the parting lines, which emerge on the blow molded article for automotive exterior panel, can be easily eliminated by an ordinary treatment such as sanding. If the amount of the inorganic filler is less than 3% by weight, the surface of the molded article cannot be finished to the prescribed surface roughness because of the formation of, for example, splits when the parting lines are being eliminated by sanding or the like. On the contrary, if the amount of the inorganic filler is more than 35% by weight, the molded article becomes so hard that disadvantages, such as reduction in the smoothness of the paint film, reduction in formability and impairment of physical properties of the product emerge.

In the prior art, as shown in FIG. 1(a), a parison 5, is extruded from an extrusion head 10 into the space between mold halves 35, 40. An exploded view of the parison surface is illustrated in FIG. 1(b). The rough surface, die lines, and granular structures are evident on the external face of the parison, which has irregular and relatively large concavities/convexities such that the surface roughness exceeds 10 μm and the peak-to-peak distance is exceeds 150 μm.

The rough surface is caused by the flow of fused resin passing through the extrusion head 10 when the parison 5 is extruded and the rough surface is made up of irregular concave and convex portions having a height of about 2 μm or greater. The die line is caused by the junction of fused resin in the direction of flow thereof in the extrusion head 10 when the parison 5 is extruded and the die line is a streaky dent having a depth in the range of from 2 to 500 μm. The granular structure is caused by an unmelted particle or carbide of resin and the granular structure is a 2 to 1000 μm protrusion or dent on the external face of parison 5.

Once the mold is closed, and the parison 5 is sandwiched between the mold halves 35, 40, a blow molded article 50 for an automotive exterior panel is produced, as shown in FIG. 2(a). The inner surface 15, 20 of mold halves 35, 40 have a mirror finish in the prior art, and the imperfections of the parison are transferred to the final product, resulting in spot marks and line marks. If the mold halves are properly treated with heating, the spot marks and line marks can be alleviated, but the heating process produces air marks, also resulting in unsatisfactory product.

The prior art finished article 50 that results after the mold halves 35, 40 have compressed and released, produce an article with a rough surface as shown in FIG. 3, The paint surface 110 follows the rough and irregular mold surface 100 to produce an article of shoddy appearance. The mold surface and/or the paint surface can be sanded and produce a smoother appearance, but this is an extra process and significantly increases production costs.

The prior art also discusses using an irregular minute concavities/convexities having a depth in the range of from 2 to 100 μm, by means of a mold which is heated to a temperature higher than the crystallization temperature of the resin and the surface of which is mirror-finished to a roughness of 0.5 μm or less. The final product using this system is also not acceptable quality.

The present invention is shown in FIG. 4, where a parison 5, which is composed of a noncrystalline resin exhibiting a tensile modulus of 2000 Kg/cm² or more at 75° C., is extruded from an extrusion head 10 into the space between mold halves 35, 40.

Once the mold is closed, and the parison 5 is sandwiched between the mold halves 35, 40. In FIG. 5(a), a blow molded article 50 is produced by a blow-molding operation comprising introducing pressurized air having a pressure of 7 Kg/cm² into the parison 5 through a blowing-in needle, which is not shown, so as to inflate the parison 5 to thereby cause the parison 5 to adhere to the cavities 15, 20.

An exploded view of the minute concavities/convexities of the inner cavities of the mold halves surface 15, 20 is illustrated in FIG. 5(b), with the minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm.

In this step, it is important to set the surface temperature Y° C. of the cavities 15, 20 to a temperature within the range Y=(0.96 X+3) to (0.96 X+40), by using a heating means which is transmitted through cavities or ducts 25, 30. The heating medium includes heated water, steam or an oil, where X° C. is a temperature at which the tensile modulus of the noncrystalline resin is 2000 Kg/cm², at the time when the parison 5 is adhered to the cavities 15, 20 or after the parison 5 is adhered to the cavities 15, 20.

Following the thermal process, a blow molded article 50 for automotive exterior panel is cooled in the mold halves 35, 40 and the mold is then opened as shown in FIG. 5(a). Next, the molded article 50 is taken out and unnecessary flushes are removed.

As a modified method for obtaining a molded article 50 for automotive exterior panel, which is free of deformation after release from the mold and which has a beautiful appearance, the cavity surface temperature Z° C., at which a mold opening process is completed for taking out the molded article for automotive exterior panel, is set to a temperature in the range of Z≦0.9X where X° C. is a temperature at which the tensile modulus of the noncrystalline resin is 2000 Kg/cm². Finally, a paint is applied to the external surface of the molded article 50 for automotive exterior panel to thereby produce a superior automotive exterior panel.

The details of the second embodiment of the method of the present invention for producing the automotive exterior panel described as follows. As shown in FIG. 4, a parison 5, which is composed of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C., is extruded from an extrusion head 2 into the space between mold halves 35, 40 whose cavities 15, 20 have minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the peak-to-peak distance is in the range of from 10 to 150 μm.

The mold is closed, and the parison 5 is sandwiched between the mold halves 35, 40. Next, a blow molded article 50 for automotive exterior panel is produced by a blow molding operation comprising introducing pressurized air having a pressure of 7 Kg/cm² into the parison 5 through a blowing-in needle, which is not shown, so as to inflate the parison 5 to thereby cause the parison 5 to adhere to the cavities 15, 20.

In this step, the surface temperature y° C. of the cavities 15, 20, which hold the parison 5 adhered thereto, is raised to a temperature within the range A<y<1.07B by using a heating ducts 25, 30 which is provided in the cavities 35, 40 and which utilizes a heating means such as heated water, steam or a heated oil, where A is a peak crystallization temperature (° C.) in a DSC curve (defined at Japan Industrial Standard (JIS) K 7121) of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.; and B is a peak fusion temperature (° C.) in a DSC curve (defined at JIS K 7121) of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.

Next, a hollow molded article 50 for automotive exterior panel is cooled in the mold halves 35, 40 and the mold is then opened as shown in FIG. 5(a). Then, the blow molded article 50 is taken out and unnecessary flushes are removed.

In this step, a molded article 50 for automotive exterior panel, which is free of deformation after release from the mold and which has a beautiful appearance, can be obtained, if the cavity (15, 20) surface temperature z° C., at which a mold opening process is started for taking out the molded article for automotive exterior panel, is set to a temperature in the range of z≦A−15.

After removing the article, parting line portions are removed by sanding and thereafter a paint is applied at a thickness of from 15 to 150 μm to the external surface of the molded article 50 for automotive exterior panel to thereby produce a superior automotive exterior panel.

The details of the third embodiment of the method of the present invention for producing the automotive exterior panel are shown in FIG. 4, wherein a parison 5, which is composed of a crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C., is extruded from an extrusion head 10 into the space between mold halves 35, 40. The mold halves 35, 40 have cavities 15, 20 with minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm.

The mold halves 35, 40 are closed, and the mold is heated by using heating ducts 25, 30 so that the surface temperature y° C. of the cavities 15, 20 at the point immediately before the mold closure is a temperature within the range A<y<1.07B, where A is a peak crystallization temperature (° C.) in a DSC curve (defined at JIS K 7121) of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.; and B is a peak fusion temperature (° C.) in a DSC curve (defined at JIS K 7121) of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.

After the mold halves 35, 40 are closed, a hollow molded article 50 for automotive exterior panel is produced by a blow-molding process comprising introducing pressurized air having a pressure of 7 Kg/cm² into the parison 5 through a blowing-in needle, which is not shown, so as to inflate the parison 5 to thereby cause the parison 5 to adhere to the cavities 15, 20.

The hollow molded article 50 for automotive exterior panel is cooled in the mold halves 35, 40 and the mold is then opened as shown in FIG. 5(a). Next, the molded article 50 is taken out and unnecessary burrs are removed.

The molded article 50 for automotive exterior panel, which is free of deformation after release from the mold and which has a beautiful appearance, can be obtained if the cavity surface temperature z° C., at which a mold opening process is started for taking out the molded article for automotive exterior panel, is set to a temperature in the range of z≦A−15.

Any parting line portions are removed by sanding and thereafter paint is applied at a thickness of from 15 to 150 μm to the external surface of the molded article 50 for automotive exterior panel to thereby produce a superior automotive exterior panel.

The work product of the present method is shown in FIG. 6. The mold surface 120 has minute concavities/convexities such that the overall peak to valley distance (Rt) is less than 10 μm, and the peak-to-peak distance (Sm) is less than 150 μm. The paint surface 130 has a smooth surface that does not require any additional sanding. The smooth surface results from the present invention, wherein the paint fills in the minute concavities/convexities by a capillary action.

The term “automotive exterior panel” as used herein means a spoiler, a bumper, a trunk lid, a side mole, a fender, a bonnet, and the like, for which so-called good appearance, such as glossy surface, brilliant color, and the like, is strictly required.

In the present invention, the tensile strength refers to a value obtained by a tensile rate of 2 mm/minute by using a No. 2 type test piece in accordance with JIS K 7113. Even if the test pieces belong to the same noncrystalline resin, the tensile strength differs depending on the individual properties of resin for the test pieces. A noncrystalline resin, which exhibits a tensile modulus of 2000 Kg/cm² or more at 75° C. or preferably at 85° C. or above, is excellent in heat resistance. Examples of these resins include modified polyphenylene oxide, polycarbonate, noncrystalline polyamide, ABS resins, and polysulfone. Examples of a blend comprising a noncrystalline resin includes a blend of an ABS resin and polycarbonate.

In the present invention, the noncrystalline resin may be a blend of a noncrystalline resin and a crystalline resin wherein the noncrystalline component accounts for 30% by weight or more and wherein the blend exhibits a tensile modulus of 2000 Kg/cm² or more at 75° C. Examples of the blend of a noncrystalline resin and a crystalline resin include a blend of modified polyphenylene oxide and polyamide and a blend of polycarbonate and polybutylene terephthalate.

The flexural modulus at 23° C. in the present invention is a value obtained in accordance with JIS K 7171. A crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C. meets the mechanical strengths, such as rigidity, required for an automotive exterior panel. Examples of these resins include a single resin, such as polypropylene, high-density polyethylene, polyamide (e.g., nylon) and polybutylene-terephthalate; a blend (alloy) of a crystalline resin and a noncrystalline resin wherein the crystalline resin accounts for 30% by weight or more; and a blend (alloy) of these crystalline resins. Examples of a blend (alloy) of a crystalline resin and a noncrystalline resin include a polyamide-modified polyphenylene ether blend and a polypropylene-polystyrene blend. Examples of a blend (alloy) of crystalline resins include a polypropylene-polyethylene blend.

In the present invention, the peak crystallization temperature is a peak crystallization temperature in a DSC curve in accordance with JIS K 7121, and the peak fusion temperature is a peak fusion temperature in a DSC curve in accordance with JIS K 7121. In the case of a blend (alloy) of a crystalline resin and a noncrystalline resin, the peak crystallization temperature and the peak fusion temperature of the crystalline resin constituting the blend (alloy) are indicated as the peak crystallization temperature and the peak fusion temperature of the blend (alloy), respectively. In the case of a blend (alloy) of crystalline resins and noncrystalline resins, it has been found that the peak crystallization temperature and the peak fusion temperature, which are each sought from the additive average corresponding to the blending ratio of each crystalline resin, can serve as the peak crystallization temperature and the peak fusion temperature of the blend (alloy), respectively.

For example, the peak fusion temperature B of a blend resin, in which a crystalline resin (a) has a blending ratio of a % and a peak fusion temperature t₁, while other crystalline resin (b) has a peak fusion temperature t₂, is expressed as follows:

B=(a/100)t ₁+(1−b/100)t ₂

However, in the case where the peak fusion temperatures of the two crystalline resins (a) and (b) are so close to each other that the peaks in the DSC curves are not clearly differentiated from each other, the top of the peaks of the DSC curves was taken as the peak fusion temperature of the blend. In a similar way, the peak crystallization temperature can be obtained.

Table 1 shows the peak crystallization temperature and the peak fusion temperature of representative crystalline resins for use in the present invention.

TABLE 1 PEAK CRYSTALLIZATION PEAK FUSION CRYSTALLINE TEMPERATURE (° C.) TEMPERATURE (° C.) RESINS A B POLYPROPYLENE 115 162 HIGH-DENSITY 121 130 POLYETHYLENE POLYAMIDE 192 222 (6 NYLON) POLYBUTYLENE 198 217 TEREPHTHALATE

 

The surface irregularities formed on the outer face of blow molded automotive exterior panel and the minute concavities/convexities on the cavity of mold comprise a surface roughness in the range of from 0.9 to 9.0 μm, respectively. The surface roughness is based on maximum heights obtained by testing the surface of the cavity and blow molded article with an electrical roughness tester based on a needle tracer method (JIS B 0601), and more specifically, the surface roughness is calculated from the sum of the maximum height of the peak (convexity) and the maximum depth (concavity) of the irregularities on the outer face or on the minute concavities/convexities.

Since the surface of a blow molded article in particular often exhibits a gentle slope, the maximum height Rmax (JIS B 0601) of sectional-area curve is not used for expressing the surface roughness in the present invention. Instead, the present invention uses the sum of the maximum height of the peak (convexity) and the maximum depth (concavity), sought from the roughness curve (JIS B 0601), for expressing the surface roughness. In this case, the cut-off value of the roughness curve was 0.8 mm.

The average peak-to-peak distance of the irregularities formed on the outer face of the blow molded article for automotive exterior panel and the average peak-to-peak distance of the minute concavities/convexities of the cavity of mold for use in the present invention are in the range of from 10 to 150 μm. The average peak-to-peak distance is an average distance obtained by testing the surface of the cavity and blow molded article with an electrical roughness tester based on a needle tracer method. For the measurement, five sites were arbitrarily selected and the measurements were conducted for a breadth of 4 mm for each site.

The average peak-to-peak distance Sm is the average of distances between a peak point facing a valley and a next peak point facing a valley in cross sections traversing parallel lines in the portions for measurement cut out of a sectional-area curve (JIS B 0601). In this case, the multiplying factor in longitudinal relation to the roughness was 20000 or 10000, while the multiplying factor in transverse relation to the roughness was 50.

For the purpose of creating minute concavities/convexities having a surface roughness in the range of from 0.9 to 9.0 μm and an average peak-to-peak distance in the range of from 10 to 150 μm, an appropriate surface treatment is sand blasting by using sand having sizes in the range of from #150-grit to #1000-grit.

The application of paint to the external face of the molded article for automotive exterior panel is conducted by forming a 15 to 150 μm thick paint film by a conventional procedure using an air-spray gun. The paint adheres to the minute concavities/convexities through a capillary action and creates a smooth appearance.

EXAMPLES

In order to confirm the effects of the present invention, the following experiments were conducted, and the results are explained below.

In the experiments, blow molded articles 150 for spoiler as shown in FIG. 7, each having a length L of 1200 mm, and a breadth D of 180 mm, a height H of 90 mm and an average wall thickness of 3 mm, were prepared by blow molding using a blow-molding machine equipped with an extruder having a screw whose diameter was 90 mm. Spoilers were prepared by painting the external face of the molded articles 150 for spoiler at a paint film thickness of 50 μm.

In Examples 1-5, minute concavities/convexities were formed on the cavity of a mold by sand blasting so that the surface roughness was 5.0 μm and the average peak-to-peak distance was 25 μm. A parison of an ABS resin (YM-254 having X of 105° C. and manufactured by Technopolymer Co., Ltd.) was extruded at 240° C. and samples were prepared by changing the cavity surface temperature.

Example 6 is a comparative example to be compared with Example 2. In Example 6, the procedure of Example 2 was repeated to prepare samples, except that the cavity of the mold used in Example 6 had a mirror-finished cavity surface.

In Example 7, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mold used in Example 7 had minute concavities/convexities on the cavity such that the surface roughness was 1.0 μm and the average peak-to-peak distance was 9.0 μm.

In Example 8, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mold used in Example 8 had minute concavities/convexities on the cavity such that the surface roughness was 1.0 μm and the average peak-to-peak distance was 10 μm.

In Example 9, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mold used in Example 9 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 μm and the average peak-to-peak distance was 150 μm.

In Example 10, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mold used in Example 10 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 μm and the average peak-to-peak distance was 160 μm.

In Example 11, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mold used in Example 11 had minute concavities/convexities on the cavity such that the surface roughness was 0.9 μm and the average peak-to-peak distance was 25 μm.

In Example 12, Samples 1-9 were prepared by repeating the procedure of Example 2, except that the mold used in Example 12 had minute concavities/convexities on the cavity such that the surface roughness was 0.8 μm and the average peak-to-peak distance was 25 μm.

In Examples 13-15, minute concavities/convexities were formed on the cavity of a mold by sand blasting so that the surface roughness was 5.0 μm and the average peak-to-peak distance was 25 μm. A parison of a modified PPO resin (Noryl EBM-9201 having X of 114° C. and manufactured by Japan GE Plastics Co., Ltd.) was extruded at 240° C. and samples were prepared by changing the cavity surface temperature.

In Examples 16-22, minute concavities/convexities were formed on the cavity of a mold by sand blasting so that the surface roughness was 5.0 μm and the average peak-to-peak distance was 25 μm. A parison made of a polypropylene resin (EC-9 having A of 11 5° C. and B of 162° C. and manufactured by Nippon Polychem Co., Ltd.) incorporated with 10% by weight of talc as an inorganic filler was extruded at 220° C. and samples were prepared by changing the cavity surface temperature.

In Example 23, Samples 1-9 were prepared by using a mold which had minute concavities/convexities on the cavity such that the surface roughness was 5.0 μm and the average peak-to-peak distance was 25 μm and by changing the content of the inorganic filler while keeping the cavity surface temperature constant.

In Example 24, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 24 had minute concavities/convexities on the cavity such that the surface roughness was 2.0 μm and the average peak-to-peak distance was 10 μm.

In Example 25, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 25 had minute concavities/convexities on the cavity such that the surface roughness was 1.0 μm and the average peak-to-peak distance was 10 μm.

In Example 26, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 26 had minute concavities/convexities on the cavity such that the surface roughness was 0.9 μm and the average peak-to-peak distance was 10 μm.

In Example 27, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 27 had minute concavities/convexities on the cavity such that the surface roughness was 0.8 μm and the average peak-to-peak distance was 10 μm.

In Example 28, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 28 had minute concavities/convexities on the cavity such that the surface roughness was 9.0 μm and the average peak-to-peak distance was 30 μm.

In Example 29, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 29 had minute concavities/convexities on the cavity such that the surface roughness was 10 μm and the average peak-to-peak distance was 30 μm.

In Example 30, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 30 had minute concavities/convexities on the cavity such that the surface roughness was 3.0 μm and the average peak-to-peak distance was 10 μm.

In Example 31, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 31 had minute concavities/convexities on the cavity such that the surface roughness was 3.0 μm and the average peak-to-peak distance was 9 μm.

In Example 32, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 32 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 μm and the average peak-to-peak distance was 150 μm.

In Example 33, Samples 1-9 were prepared by repeating the procedure of Example 20, except that the mold used in Example 33 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 μm and the average peak-to-peak distance was 160 μm.

In Example 34, minute concavities/convexities were formed on the cavity of a mold by sand blasting so that the surface roughness was 5.0 μm and the average peak-to-peak distance was 25 μm. Sample 1-9 were prepared by extruding a parison made of a polypropylene-high-density polyethylene blend resin at 210° C. and by changing the cavity surface temperature. The polypropylene-high-density polyethylene blend resin was prepared by blending polypropylene resin (EC-9 having A of 115° C. and B of 162° C. and manufactured by Nippon Polychem Co., Ltd.) and high-density polyethylene (B-970 having A of 121° C. and B of 130° C. and manufactured by Asahi Chemical Industry Co., Ltd.) at a ratio of 70:30. The peak temperatures of the blend resin were 116.8° C. for A and 152.4° C. for B.

In Example 35, Samples 1-9 were prepared by repeating the procedure of Example 34, except the content of the inorganic filler in Example 35 was changed while keeping the cavity surface temperature constant.

In Example 36, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 36 had minute concavities/convexities on the cavity such that the surface roughness was 2.0 μm and the average peak-to-peak distance was 10 m.

In Example 37, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 37 had minute concavities/convexities on the cavity such that the surface roughness was 1.0 μm and the average peak-to-peak distance was 10 μm.

In Example 38, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 38 had minute concavities/convexities on the cavity such that the surface roughness was 0.9 μm and the average peak-to-peak distance was 10 μm.

In Example 39, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 39 had minute concavities/convexities on the cavity such that the surface roughness was 0.8 μm and the average peak-to-peak distance was 10 μm.

In Example 40, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 40 had minute concavities/convexities on the cavity such that the surface roughness was 9.0 μm and the average peak-to-peak distance was 30 μm.

In Example 41, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 41 had minute concavities/convexities on the cavity such that the surface roughness was 10 μm and the average peak-to-peak distance was 30 μm.

In Example 42, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 42 had minute concavities/convexities on the cavity such that the surface roughness was 3.0 μm and the average peak-to-peak distance was 9 μm.

In Example 43, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 43 had minute concavities/convexities on the cavity such that the surface roughness was 3.0 μm and the average peak-to-peak distance was 10 μm.

In Example 44, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 44 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 μm and the average peak-to-peak distance was 150 μm.

In Example 45, Samples 1-9 were prepared by repeating the procedure of Example 34, except that the mold used in Example 45 had minute concavities/convexities on the cavity such that the surface roughness was 5.0 μm and the average peak-to-peak distance was 160 μm.

The evaluation results of Examples 1-45 are shown in Tables 2-1-Tables 2-45.

In Tables 2-1-Tables 2-45, evaluation criteria are as follows:

In the tables:

Rt—indicates the surface roughness in μm;

Sm—indicates an average peak-to-peak distance in μm of the irregularities on the surface of molded articles.

Note: Deformation, surface condition, air marks, die lines, and bits were visually inspected after blow molding but before painting the molded articles.

Deformation

NONE: no deformation observed

SOME: slight deformation but judged as acceptable

YES: deformation observed

Surface condition

NONE: no shark skin irregularities observed on the surface and the surface is uniform

SOME: slight shark skin irregularities observed on the surface

YES: remarkable shark skin irregularities observed on the surface

Air marks

NONE: no air mark observed

SOME: almost no air mark observed

YES: air mark observed

Die lines

NONE no die line observed

SOME: almost no die line observed

YES: die lines observed

Bits

NONE: no bits observed

SOME: almost no bits observed

YES: bits observed

Appearance of paint film

NONE: no orange peel observed

SOME: slight orange peel observed

YES: orange peel observed

TABLE 2-1 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Die of Example Z Y Second Deformation Condition Air Mark Line Bit Rt Sm Paint Film Example 1-1 60  70 140 NONE YES NONE YES YES 6.4 190 YES Example 1-2 60  80 140 NONE YES NONE YES YES 5.8 188 YES Example 1-3 60  90 140 NONE YES NONE YES YES 5.4 185 SOME Example 1-4 60 100 140 NONE YES NONE YES YES 5.3 158 SOME Example 1-5 60 105 140 NONE SOME NONE NONE SOME 4.9 148 NONE Example 1-6 60 115 140 NONE NONE NONE NONE NONE 5.2 124 NONE Example 1-7 60 125 140 NONE NONE NONE NONE NONE 5.0  70 NONE Example 1-8 60 135 150 NONE NONE NONE NONE NONE 4.9  66 NONE Example 1-9 60 145 180 NONE NONE NONE NONE NONE 5.1  25 NONE

 

TABLE 2-2 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 2-1 70  70 120 NONE YES NONE YES YES 5.8 210 YES Example 2-2 70  80 120 NONE YES NONE YES YES 6.1 204 YES Example 2-3 70  90 120 NONE YES NONE YES YES 5.4 182 YES Example 2-4 70 100 120 NONE YES NONE YES YES 5.2 160 SOME Example 2-5 70 105 120 NONE SOME NONE NONE SOME 5.4 141 NONE Example 2-6 70 115 120 NONE NONE NONE NONE NONE 4.9 110 NONE Example 2-7 70 125 120 NONE NONE NONE NONE NONE 5.0  60 NONE Example 2-8 70 135 140 NONE NONE NONE NONE NONE 4.8  45 NONE Example 2-9 70 145 160 NONE NONE NONE NONE NONE 5.0  24 NONE

 

TABLE 2-3 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 3-1 80  80 120 NONE YES NONE YES YES 5.6 191 YES Example 3-2 80  90 120 NONE YES NONE YES YES 5.8 175 SOME Example 3-3 80 100 120 NONE YES NONE SOME YES 6.1 154 SOME Example 3-4 80 105 120 NONE SOME NONE NONE NONE 5.4 138 NONE Example 3-5 80 115 120 NONE NONE NONE NONE NONE 5.2  60 NONE Example 3-6 80 125 120 NONE NONE NONE NONE NONE 4.9  32 NONE Example 3-7 80 135 130 NONE NONE NONE NONE NONE 5.0  28 NONE Example 3-8 80 145 150 NONE NONE NONE NONE NONE 5.0  25 NONE

 

TABLE 2-4 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 4-1 90  90 120 NONE SOME NONE YES YES 5.5 178 YES Example 4-2 90 100 120 NONE SOME NONE SOME SOME 5.8 168 SOME Example 4-3 90 105 120 NONE SOME NONE NONE NONE 5.7 134 NONE Example 4-4 90 115 120 NONE NONE NONE NONE NONE 5.3  75 NONE Example 4-5 90 125 130 NONE NONE NONE NONE NONE 5.2  35 NONE Example 4-6 90 135 150 NONE NONE NONE NONE NONE 5.2  27 NONE Example 4-7 90 145 175 NONE NONE NONE NONE NONE 5.2  26 NONE

 

TABLE 2-5 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 5-1 95 100 130 YES SOME NONE SOME YES 5.3 158  YES Example 5-2 95 105 130 YES SOME NONE NONE SOME 5.6 125  NONE Example 5-3 95 115 160 YES SOME NONE NONE NONE 5.4 84 NONE Example 5-4 95 125 190 YES NONE NONE NONE NONE 5.2 45 NONE Example 5-5 95 135 200 YES NONE NONE NONE NONE 5.0 32 NONE Example 5-6 95 145 200 YES NONE NONE NONE NONE 4.9 28 NONE

 

TABLE 2-6 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 6-1 70  70 120 NONE YES NONE YES YES 5.4 185 YES Example 6-2 70  80 120 NONE YES NONE YES YES 5.2 176 YES Example 6-3 70  90 120 NONE YES NONE YES YES 4.2 170 YES Example 6-4 70 100 120 NONE YES NONE YES YES 2.4 168 YES Example 6-5 70 105 120 NONE SOME NONE NONE SOME 1.9 146 SOME Example 6-6 70 115 120 NONE NONE SOME NONE NONE 1.2 194 SOME Example 6-7 70 125 120 NONE NONE SOME NONE NONE 0.9 222 SOME Example 6-8 70 135 140 NONE NONE YES NONE NONE 0.6 201 YES Example 6-9 70 145 160 NONE NONE YES NONE NONE 0.6 176 YES

 

TABLE 2-7 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 7-1 70  70 120 NONE YES NONE YES YES 5.8 196 YES Example 7-2 70  80 120 NONE YES NONE YES YES 5.4 199 YES Example 7-3 70  90 120 NONE YES NONE YES YES 6.0 182 YES Example 7-4 70 100 120 NONE YES NONE YES YES 5.8 168 YES Example 7-5 70 105 120 NONE SOME NONE NONE SOME 5.9 125 SOME Example 7-6 70 115 120 NONE NONE SOME NONE SOME 5.5 69 SOME Example 7-7 70 125 120 NONE NONE SOME NONE NONE 5.4 48 SOME Example 7-8 70 135 140 NONE NONE SOME NONE NONE 3.6 28 SOME Example 7-9 70 145 160 NONE NONE SOME NONE NONE 1.2 10.5 SOME

 

TABLE 2-8 Temper- Evaluation ature Molding Condition of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Coated Surface Example 8-1 70  70 120 NONE YES NONE YES YES 6.0 207 YES Example 8-2 70  80 120 NONE YES NONE YES YES 5.5 200 YES Example 8-3 70  90 120 NONE YES NONE YES YES 5.4 188 YES Example 8-4 70 100 120 NONE YES NONE YES YES 5.9 159 YES Example 8-5 70 105 120 NONE SOME NONE NONE SOME 6.4 124 SOME Example 8-6 70 115 120 NONE NONE SOME NONE SOME 5.4 69 SOME Example 8-7 70 125 120 NONE NONE SOME NONE NONE 4.8 45 SOME Example 8-8 70 135 140 NONE NONE SOME NONE NONE 1.8 24 SOME Example 8-9 70 145 160 NONE NONE SOME NONE NONE 1.2 10.6 SOME

 

TABLE 2-9 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 9-1 70  70 120 NONE YES NONE YES YES 5.8 202 YES Example 9-2 70  80 120 NONE YES NONE YES YES 6.1 180 YES Example 9-3 70  90 120 NONE YES NONE YES YES 5.9 175 YES Example 9-4 70 100 120 NONE YES NONE YES YES 6.4 165 YES Example 9-5 70 105 120 NONE SOME NONE NONE SOME 5.6 158 SOME Example 9-6 70 115 120 NONE NONE NONE NONE NONE 6.2 155 SOME Example 9-7 70 125 120 NONE NONE SOME NONE NONE 5.8 153 SOME Example 9-8 70 135 140 NONE NONE SOME NONE NONE 5.0 156 SOME Example 9-9 70 145 160 NONE NONE SOME NONE NONE 4.9 154 SOME

 

TABLE 2-10 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 10-1 70  70 120 NONE YES NONE YES YES 6.1 200 YES Example 10-2 70  80 120 NONE YES NONE YES YES 5.9 198 YES Example 10-3 70  90 120 NONE YES NONE YES YES 5.4 195 YES Example 10-4 70 100 120 NONE YES NONE YES YES 6.8 186 YES Example 10-5 70 105 120 NONE SOME NONE NONE SOME 5.4 188 YES Example 10-6 70 115 120 NONE NONE NONE NONE NONE 6.4 173 YES Example 10-7 70 125 120 NONE NONE SOME NONE NONE 5.8 168 YES Example 10-8 70 135 140 NONE NONE NONE NONE NONE 4.9 164 YES Example 10-9 70 145 160 NONE NONE NONE NONE NONE 5.2 160 YES

 

TABLE 2-11 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 11-1 70  70 120 NONE YES NONE YES YES 5.3 198 YES Example 11-2 70  80 120 NONE YES NONE YES YES 5.1 192 YES Example 11-3 70  90 120 NONE YES NONE YES YES 4.8 176 YES Example 11-4 70 100 120 NONE YES NONE YES YES 3.1 154 YES Example 11-5 70 105 120 NONE SOME NONE NONE SOME 1.9 130 SOME Example 11-6 70 115 120 NONE NONE NONE NONE NONE 1.0  65 NONE Example 11-7 70 125 120 NONE NONE NONE NONE NONE 0.9  32 NONE Example 11-8 70 135 140 NONE NONE SOME NONE NONE 0.8  27 SOME Example 11-9 70 145 160 NONE NONE SOME NONE NONE 0.9  25 SOME

 

TABLE 2-12 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 12-1 70  70 120 NONE YES NONE YES YES 5.4 197 YES Example 12-2 70  80 120 NONE YES NONE YES YES 5.1 191 YES Example 12-3 70  90 120 NONE YES NONE YES YES 4.2 169 YES Example 12-4 70 100 120 NONE YES NONE YES YES 2.4 155 YES Example 12-5 70 105 120 NONE SOME NONE NONE SOME 1.9 129 SOME Example 12-6 70 115 120 NONE NONE SOME NONE SOME 1.5  84 SOME Example 12-7 70 125 120 NONE NONE SOME NONE NONE 0.8  36 SOME Example 12-8 70 135 140 NONE NONE SOME NONE NONE 0.7  27 SOME Example 12-9 70 145 160 NONE NONE YES NONE NONE 0.8  25 YES

 

TABLE 2-13 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 13-1 90 100 120 NONE YES NONE YES YES 12.0  289 YES Example 13-2 90 105 120 NONE YES NONE YES YES 8.6 260 YES Example 13-3 90 110 120 NONE SOME NONE NONE SOME 5.8 190 YES Example 13-4 90 115 120 NONE NONE NONE NONE NONE 5.4 149 NONE Example 13-5 90 120 120 NONE NONE NONE NONE NONE 5.2  76 NONE Example 13-6 90 130 120 NONE NONE NONE NONE NONE 4.9  40 NONE Example 13-7 90 140 140 NONE NONE NONE NONE NONE 5.0  35 NONE Example 13-8 90 150 160 NONE NONE NONE NONE NONE 5.1  28 NONE Example 13-9 90 170 180 NONE NONE NONE NONE NONE 5.0  26 NONE

 

TABLE 2-14 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 14-1 80  90 120 NONE YES NONE YES YES 12.4  304 YES Example 14-2 80 100 120 NONE YES NONE YES YES 9.4 296 YES Example 14-3 80 105 120 NONE YES NONE NONE SOME 7.0 234 YES Example 14-4 80 110 120 NONE SOME NONE NONE NONE 6.0 182 NONE Example 14-5 80 115 120 NONE SOME NONE NONE NONE 5.6 140 NONE Example 14-6 80 120 120 NONE NONE NONE NONE NONE 5.2  78 NONE Example 14-7 80 130 140 NONE NONE NONE NONE NONE 5.0  42 NONE Example 14-8 80 140 160 NONE NONE NONE NONE NONE 4.9  31 NONE Example 14-9 80 150 180 NONE NONE NONE NONE NONE 5.0  25 NONE

 

TABLE 2-15 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 15-1 70  80 120 NONE YES NONE YES YES 11.8  306 YES Example 15-2 70  90 120 NONE YES NONE YES YES 10.4  298 YES Example 15-3 70 100 120 NONE YES NONE YES YES 7.6 292 YES Example 15-4 70 105 120 NONE YES NONE SOME YES 6.9 210 YES Example 15-5 70 110 120 NONE SOME NONE NONE NONE 6.0 194 SOME Example 15-6 70 115 120 NONE NONE NONE NONE NONE 5.5 149 NONE Example 15-7 70 120 135 NONE NONE NONE NONE NONE 5.0  74 NONE Example 15-8 70 130 160 NONE NONE NONE NONE NONE 5.1  36 NONE Example 15-9 70 140 180 NONE NONE NONE NONE NONE 4.9  29 NONE

 

TABLE 2-16 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 16-1 5 110 240 NONE YES NONE YES YES 13.8  202 YES Example 16-2 5 115 240 NONE SOME NONE SOME SOME 8.6 150 SOME Example 16-3 5 120 240 NONE SOME NONE SOME SOME 7.6 136 SOME Example 16-4 5 130 240 NONE SOME NONE NONE NONE 6.3  65 NONE Example 16-5 5 140 260 NONE SOME NONE NONE NONE 5.7  32 NONE Example 16-6 5 150 260 NONE NONE NONE NONE NONE 5.2  30 NONE Example 16-7 5 160 280 NONE NONE NONE NONE NONE 5.0  26 NONE Example 16-8 5 170 280 NONE NONE NONE NONE NONE 5.3  26 NONE Example 16-9 5 175 300 NONE NONE NONE NONE NONE 5.1  27 NONE

 

TABLE 2-17 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 17-1 20 110 240 NONE YES NONE YES YES 14.1  210 YES Example 17-2 20 115 240 NONE SOME NONE SOME SOME 8.8 148 SOME Example 17-3 20 120 240 NONE SOME NONE SOME SOME 6.8 124 SOME Example 17-4 20 130 240 NONE SOME NONE NONE NONE 6.0  82 NONE Example 17-5 20 140 260 NONE SOME NONE NONE NONE 5.5  46 NONE Example 17-6 20 150 260 NONE NONE NONE NONE NONE 5.3  32 NONE Example 17-7 20 160 280 NONE NONE NONE NONE NONE 4.9  26 NONE Example 17-8 20 170 280 NONE NONE NONE NONE NONE 5.0  26 NONE Example 17-9 20 175 300 NONE NONE NONE NONE NONE 5.0  24 NONE

 

TABLE 2-18 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 18-1 30 110 230 NONE YES NONE YES YES 11.5  198 YES Example 18-2 30 115 230 NONE SOME NONE SOME SOME 7.6 143 SOME Example 18-3 30 120 230 NONE SOME NONE SOME SOME 5.9  64 SOME Example 18-4 30 130 230 NONE SOME NONE NONE NONE 5.4  32 NONE Example 18-5 30 140 250 NONE SOME NONE NONE NONE 5.0  30 NONE Example 18-6 30 150 250 NONE NONE NONE NONE NONE 4.9  24 NONE Example 18-7 30 160 270 NONE NONE NONE NONE NONE 5.2  25 NONE Example 18-8 30 170 270 NONE NONE NONE NONE NONE 5.0  26 NONE Example 18-9 30 175 300 NONE NONE NONE NONE NONE 5.1  27 NONE

 

TABLE 2-19 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 19-1 50 110 210 NONE YES NONE YES YES 10.6  164 YES Example 19-2 50 115 210 NONE SOME NONE SOME SOME 7.2 131 SOME Example 19-3 50 120 230 NONE SOME NONE SOME SOME 6.6  65 SOME Example 19-4 50 130 230 NONE NONE NONE NONE NONE 5.4  34 NONE Example 19-5 50 140 250 NONE SOME NONE NONE NONE 5.2  28 NONE Example 19-6 50 150 250 NONE NONE NONE NONE NONE 5.2  27 NONE Example 19-7 50 160 270 NONE NONE NONE NONE NONE 5.1  26 NONE Example 19-8 50 170 270 NONE NONE NONE NONE NONE 5.2  26 NONE Example 19-9 50 175 300 NONE NONE NONE NONE NONE 5.1  26 NONE

 

TABLE 2-20 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 20-1 80 110 210 NONE YES NONE YES YES 10.4  158  YES Example 20-2 80 115 210 NONE SOME NONE SOME SOME 6.8 99 SOME Example 20-3 80 120 230 NONE NONE NONE NONE NONE 6.2 49 NONE Example 20-4 80 130 230 NONE NONE NONE NONE NONE 5.8 39 NONE Example 20-5 80 140 250 NONE SOME NONE NONE NONE 5.2 30 NONE Example 20-6 80 150 250 NONE NONE NONE NONE NONE 5.0 24 NONE Example 20-7 80 160 270 NONE NONE NONE NONE NONE 5.1 25 NONE Example 20-8 80 170 270 NONE NONE NONE NONE NONE 5.1 25 NONE Example 20-9 80 175 300 NONE NONE NONE NONE NONE 5.1 24 NONE

 

TABLE 2-21 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 21-1 100 110 230 NONE YES NONE YES YES 10.0  154  YES Example 21-2 100 115 230 NONE NONE NONE NONE NONE 6.7 96 NONE Example 21-3 100 120 250 NONE NONE NONE NONE NONE 5.9 56 NONE Example 21-4 100 130 250 NONE NONE NONE NONE NONE 5.4 40 NONE Example 21-5 100 140 270 NONE SOME NONE NONE NONE 5.0 27 NONE Example 21-6 100 150 270 NONE NONE NONE NONE NONE 4.9 26 NONE Example 21-7 100 160 290 NONE NONE NONE NONE NONE 5.0 25 NONE Example 21-8 100 170 290 NONE NONE NONE NONE NONE 5.1 25 NONE Example 21-9 100 175 320 NONE NONE NONE NONE NONE 5.1 25 NONE

 

TABLE 2-22 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 22-1 105 110 230 SOME YES NONE YES SOME 9.4 155  YES Example 22-2 105 115 230 SOME NONE NONE NONE NONE 5.8 72 SOME Example 22-3 105 120 250 SOME NONE NONE NONE NONE 5.4 48 SOME Example 22-4 105 130 250 SOME NONE NONE NONE NONE 5.0 28 SOME Example 22-5 105 140 270 YES NONE NONE NONE NONE 4.9 26 YES Example 22-6 105 150 270 YES NONE NONE NONE NONE 5.1 25 YES Example 22-7 105 160 290 YES NONE NONE NONE NONE 5.1 26 YES Example 22-8 105 170 290 YES NONE NONE NONE NONE 5.1 26 YES Example 22-9 105 175 320 YES NONE NONE NONE NONE 5.0 26 YES

 

It can be seen from Tables 2-16 -Tables 2-22 that the molding time rises to 300 seconds if the cavity surface temperature Y° C. reaches 175° C. while the parison adheres to the cavity. Further, it can be seen from Table 2-21 that the deformation of the molded article emerges and therefore the paint film appearance of the molded article becomes inferior if Z° C., which indicates the cavity surface temperature at the time when a mold opening process is started for taking out the molded article for automotive exterior panel, exceeds 100° C.

TABLE 2-23 Temper- Evaluation ature Content Sanding Molding Appearance of Cavity of Filler Time Time Surface Air Die of Example Z Y % Minute Second Deformation Condition Mark Line Bit Rt Sm Paint Film 23-1 70 125  0 40 230 NONE NONE NONE NONE NONE 6.0 50 NONE 23-2 70 125  1 40 230 NONE NONE NONE NONE NONE 6.0 52 NONE 23-3 70 125  2 39 230 NONE NONE NONE NONE NONE 6.0 53 NONE 23-4 70 125  3 26 230 NONE NONE NONE NONE NONE 6.1 49 NONE 23-5 70 125  5 20 230 NONE NONE NONE NONE NONE 6.2 50 NONE 23-6 70 125 30 15 230 NONE NONE NONE NONE NONE 6.2 50 NONE 23-7 70 125 35 15 230 NONE NONE NONE NONE NONE 6.3 49 NONE 23-8 70 125 40 10 230 NONE NONE NONE NONE NONE 6.4 51 YES 23-9 70 125 50 — — — — — — — — — —

 

In Table 2-23, if the filler content exceeds 40% by weight, elongation of the parison becomes inferior and therefore rough surface is generated in the surface. As a result, the paint film appearance of the molded article becomes inferior. The elongation of Sample 9 whose filler content was 50% by weight was so poor that Sample 9 could not be molded because holes were formed in the article during the molding operation.

Based on these results it can be seen that, if the filler content exceeds 35% by weight, elongation of the parison becomes extremely inferior and therefore the paint film appearance of the molded article becomes inferior because of the inferior surface condition of the molded article. To the contrary, it can be seen that, if the filler content is less than 3% by weight, the time required for sanding the parting lines is as long as about 40 minutes.

TABLE 2-24 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 24-1 70 110 210 NONE YES NONE YES YES 10.8  166  YES Example 24-2 70 115 210 NONE SOME NONE SOME SOME 7.4 134  SOME Example 24-3 70 120 230 NONE NONE NONE NONE NONE 6.6 59 NONE Example 24-4 70 130 230 NONE NONE NONE NONE NONE 5.5 30 NONE Example 24-5 70 140 250 NONE NONE NONE NONE NONE 4.6 24 NONE Example 24-6 70 150 250 NONE NONE NONE NONE NONE 2.1 12 NONE Example 24-7 70 160 270 NONE NONE NONE NONE NONE 2.1 10 NONE Example 24-8 70 170 270 NONE NONE NONE NONE NONE 2.2 11 NONE Example 24-9 70 175 280 NONE NONE NONE NONE NONE 2.1 11 NONE

 

TABLE 2-25 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 25-1 70 110 210 NONE YES NONE YES YES 10.6  169 YES Example 25-2 70 115 210 NONE SOME NONE SOME SOME 7.6 136 SOME Example 25-3 70 120 230 NONE NONE NONE NONE NONE 6.5  59 NONE Example 25-4 70 130 230 NONE NONE NONE NONE NONE 5.4  42 NONE Example 25-5 70 140 250 NONE NONE NONE NONE NONE 2.8  28 NONE Example 25-6 70 150 250 NONE NONE NONE NONE NONE 1.2  10 NONE Example 25-7 70 160 270 NONE NONE NONE NONE NONE 0.9  11 NONE Example 25-8 70 170 270 NONE NONE NONE NONE NONE 1.0  10 NONE Example 25-9 70 175 280 NONE NONE NONE NONE NONE 1.1  11 NONE

 

TABLE 2-26 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 26-1 70 110 210 NONE YES NONE YES YES 11.8  165  YES Example 26-2 70 115 210 NONE SOME NONE SOME SOME 7.4 144  SOME Example 26-3 70 120 230 NONE NONE NONE NONE NONE 6.0 61 NONE Example 26-4 70 130 230 NONE NONE NONE NONE NONE 5.5 40 NONE Example 26-5 70 140 250 NONE NONE NONE NONE NONE 2.4 27 NONE Example 26-6 70 150 250 NONE NONE NONE NONE NONE 1.2 14 NONE Example 26-7 70 160 270 NONE NONE SOME NONE NONE 1.1 11 SOME Example 26-8 70 170 270 NONE NONE SOME NONE NONE 1.1 11 SOME Example 26-9 70 175 280 NONE NONE SOME NONE NONE 1.1 10 SOME

 

TABLE 2-27 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 27-1 70 110 210 NONE YES NONE YES YES 12.0  184  YES Example 27-2 70 115 210 NONE SOME NONE SOME SOME 7.8 132  SOME Example 27-3 70 120 230 NONE NONE SOME NONE NONE 6.1 59 SOME Example 27-4 70 130 230 NONE NONE SOME NONE NONE 5.4 40 SOME Example 27-5 70 140 250 NONE NONE SOME NONE NONE 2.3 24 SOME Example 27-6 70 150 250 NONE NONE YES NONE NONE 1.2 12 YES Example 27-7 70 160 270 NONE NONE YES NONE NONE 0.9 10 YES Example 27-8 70 170 270 NONE NONE YES NONE NONE 0.8 11 YES Example 27-9 70 170 280 NONE NONE YES NONE NONE 0.8 11 YES

 

TABLE 2-28 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 28-1 70 110 210 NONE YES NONE YES YES 11.8  175  YES Example 28-2 70 115 210 NONE SOME NONE SOME SOME 8.0 120  YES Example 28-3 70 120 230 NONE SOME NONE NONE NONE 7.4 66 YES Example 28-4 70 130 230 NONE SOME NONE NONE NONE 8.4 35 SOME Example 28-5 70 140 250 NONE NONE NONE NONE NONE 9.3 29 NONE Example 28-6 70 150 250 NONE NONE NONE NONE NONE 9.0 30 NONE Example 28-7 70 160 270 NONE NONE SOME NONE NONE 9.1 31 NONE Example 28-8 70 170 270 NONE NONE SOME NONE NONE 8.9 31 NONE Example 28-9 70 175 280 NONE NONE SOME NONE NONE 8.9 31 NONE

 

TABLE 2-29 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 29-1 70 110 210 NONE YES NONE YES YES 12.0 189  YES Example 29-2 70 115 210 NONE SOME NONE SOME SOME  8.4 119  YES Example 29-3 70 120 230 NONE SOME NONE NONE NONE  8.6 61 YES Example 29-4 70 130 230 NONE SOME NONE NONE NONE  9.8 40 SOME Example 29-5 70 140 250 NONE NONE NONE NONE NONE 10.2 35 NONE Example 29-6 70 150 250 NONE NONE NONE NONE NONE 10.1 30 NONE Example 29-7 70 160 270 NONE NONE SOME NONE NONE 10.1 30 SOME Example 29-8 70 170 270 NONE NONE SOME NONE NONE 10.2 30 NONE Example 29-9 70 175 280 NONE NONE SOME NONE NONE 10.2 30 NONE

 

It can be seen from Tables 2-24˜Tables 2-29 that the surface roughness Rt of the minute concavities/convexities of cavity needs to be 0.9 to 9.0 μm.

Samples in Table 2-27 have extremely poor paint film appearance. Also, samples in Table 2-29 have poor paint film appearance. Based on these results, it can be seen that the surface roughness Rt of the minute concavities/convexities of cavity needs to be 0.9 to 9.0 μm.

TABLE 2-30 Evaluation Temperature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 30-1 70 110 210 NONE YES NONE YES YES 12.2  186 YES Example 30-2 70 115 210 NONE SOME NONE SOME SOME 7.8 119 SOME Example 30-3 70 120 230 NONE NONE NONE NONE NONE 6.9 70 NONE Example 30-4 70 130 230 NONE NONE NONE NONE NONE 5.2 42 NONE Example 30-5 70 140 250 NONE NONE NONE NONE NONE 3.4 24 NONE Example 30-6 70 150 250 NONE NONE NONE NONE NONE 3.2 11.0 NONE Example 30-7 70 160 270 NONE NONE NONE NONE NONE 3.0 10.0 NONE Example 30-8 70 170 270 NONE NONE NONE NONE NONE 3.1 10.2 NONE Example 30-9 70 175 280 NONE NONE NONE NONE NONE 3.1 10.2 NONE

 

TABLE 2-31 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 31-1 70 110 210 NONE YES NONE YES YES 12.4 180 YES Example 31-2 70 115 210 NONE SOME NONE SOME SOME 8.7 140 SOME Example 31-3 70 120 230 NONE NONE SOME NONE NONE 7.0 98 SOME Example 31-4 70 130 230 NONE NONE SOME NONE NONE 5.8 38 SOME Example 31-5 70 140 250 NONE NONE SOME NONE NONE 3.7 12 SOME Example 31-6 70 150 250 NONE NONE YES NONE NONE 3.2 8.9 YES Example 31-7 70 160 270 NONE NONE YES NONE NONE 2.9 8.9 YES Example 31-8 70 170 270 NONE NONE YES NONE NONE 2.9 9.0 YES Example 31-9 70 175 280 NONE NONE YES NONE NONE 2.9 9.1 YES

 

TABLE 2-32 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 32-1 70 110 210 NONE YES NONE YES YES 12.6 198 YES Example 32-2 70 115 210 NONE SOME NONE NONE NONE 7.8 160 SOME Example 32-3 70 120 230 NONE SOME NONE NONE NONE 6.4 155 SOME Example 32-4 70 130 230 NONE SOME NONE NONE NONE 5.5 149 SOME Example 32-5 70 140 250 NONE NONE NONE NONE NONE 4.9 150 NONE Example 32-6 70 150 250 NONE NONE NONE NONE NONE 5.0 150 NONE Example 32-7 70 160 270 NONE NONE NONE NONE NONE 5.0 150 NONE Example 32-8 70 170 270 NONE NONE NONE NONE NONE 5.0 150 NONE Example 32-9 70 175 280 NONE NONE NONE NONE NONE 5.0 152 NONE

 

TABLE 2-33 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 33-1 70 110 210 NONE YES NONE YES YES 12.6 202 YES Example 33-2 70 115 210 NONE SOME NONE NONE NONE 7.9 184 SOME Example 33-3 70 120 230 NONE SOME NONE NONE NONE 6.5 162 SOME Example 33-4 70 130 230 NONE SOME NONE NONE NONE 5.5 160 SOME Example 33-5 70 140 250 NONE SOME NONE NONE NONE 4.8 160 SOME Example 33-6 70 150 250 NONE NONE NONE NONE NONE 5.0 160 SOME Example 33-7 70 160 270 NONE NONE NONE NONE NONE 5.1 160 SOME Example 33-8 70 170 270 NONE NONE NONE NONE NONE 5.1 159 SOME Example 33-9 70 175 280 NONE NONE NONE NONE NONE 5.1 161 SOME

 

It can be seen from Tables 2-30 -Tables 2-33 that the average peak-to-peak distance Sm of the minute concavities/convexities of cavity needs to be 10 to 150 μm.

Samples in Table 2-31 have extremely poor paint film appearance. Also, samples in Table 2-33 have poor paint film appearance. Based on these results, it can be seen that the average peak-to-peak distance of the minute concavities/convexities of cavity needs to be 10 to 150 μm.

It can be seen from Tables 2-16-Tables 2-33 that the molded article for automotive exterior panel needs to have surface irregularities comprising a surface roughness Rt of 0.9 to 9.0 μm and an average peak-to-peak distance Sm of 10 to 150 μm.

TABLE 2-34 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 34-1 70 110 210 NONE YES NONE YES YES 12.6 202  YES Example 34-2 70 115 210 NONE SOME NONE YES YES 12.4 120  YES Example 34-3 70 120 230 NONE SOME NONE NONE NONE 6.4 58 NONE Example 34-4 70 125 230 NONE SOME NONE NONE NONE 5.8 38 SOME Example 34-5 70 130 250 NONE SOME NONE NONE NONE 5.0 25 NONE Example 34-6 70 140 250 NONE NONE NONE NONE NONE 5.0 25 NONE Example 34-7 70 150 270 NONE NONE NONE NONE NONE 5.0 26 NONE Example 34-8 70 160 270 NONE NONE NONE NONE NONE 5.1 24 NONE Example 34-9 70 165 300 NONE NONE NONE NONE NONE 5.0 25 NONE

 

TABLE 2-35 Temper- Content Evaluation ature of Sanding Molding Appearance of Cavity Filler Time Time Surface Air Die of Example Z Y % Minute Second Deformation Condition Mark Line Bit Rt Sm Paint Film 35-1 70 125  0 50 230 NONE NONE NONE NONE NONE 6.4 38 NONE 35-2 70 125  1 50 230 NONE NONE NONE NONE NONE 6.4 37 NONE 35-3 70 125  2 47 230 NONE NONE NONE NONE NONE 6.4 38 NONE 35-4 70 125  3 36 230 NONE SOME NONE NONE NONE 6.4 38 NONE 35-5 70 125  5 30 230 NONE SOME NONE NONE NONE 6.3 40 NONE 35-6 70 125 30 25 230 NONE NONE NONE NONE NONE 6.5 39 NONE 35-7 70 125 35 20 230 NONE NONE NONE NONE NONE 6.6 38 NONE 35-8 70 125 40 20 230 NONE YES NONE NONE NONE 6.6 38 YES 35-9 70 125 50 — — — — — — — — — —

 

In Table 2-35, if the filler content exceeds 40% by weight, elongation of the parison becomes inferior and therefore rough surface emerges in the surface. As a result, the paint film appearance of the molded article becomes inferior. The elongation of Sample 9 whose filler content was 50% by weight was so poor that Sample 9 could not be molded because holes were formed in the article during the molding operation.

Based on these results, it can be seen that, if the filler content exceeds 35% by weight, elongation of the parison becomes extremely inferior and therefore the paint film appearance of the molded article becomes inferior because of the inferior surface condition of the molded article. To the contrary, it can be seen that, if the filler content is less than 3% by weight, the time required for sanding the parting lines is as long as about 50 minutes.

TABLE 2-36 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 36-1 70 110 210 NONE YES NONE YES YES 12.3 195  YES Example 36-2 70 115 210 NONE SOME NONE YES YES 11.0 140  YES Example 36-3 70 120 230 NONE NONE NONE NONE NONE 6.8 48 NONE Example 36-4 70 125 230 NONE NONE NONE NONE NONE 4.9 18 NONE Example 36-5 70 130 250 NONE NONE NONE NONE NONE 2.0 11 NONE Example 36-6 70 140 250 NONE NONE NONE NONE NONE 2.0 11 NONE Example 36-7 70 150 270 NONE NONE NONE NONE NONE 2.1 11 NONE Example 36-8 70 160 270 NONE NONE NONE NONE NONE 2.1 11 NONE Example 36-9 70 165 300 NONE NONE NONE NONE NONE 2.0 11 NONE

 

TABLE 2-37 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 37-1 70 110 210 NONE YES NONE YES YES 12.4 204  YES Example 37-2 70 115 210 NONE SOME NONE YES SOME 11.2 135  YES Example 37-3 70 120 230 NONE NONE NONE NONE NONE 6.5 52 NONE Example 37-4 70 125 230 NONE NONE NONE NONE NONE 4.2 20 NONE Example 37-5 70 130 250 NONE NONE NONE NONE NONE 1.4 12 NONE Example 37-6 70 140 250 NONE NONE NONE NONE NONE 1.1 11 NONE Example 37-7 70 150 270 NONE NONE NONE NONE NONE 1.0 11 NONE Example 37-8 70 160 270 NONE NONE NONE NONE NONE 1.1 10 NONE Example 37-9 70 165 300 NONE NONE NONE NONE NONE 1.0 10 NONE

 

TABLE 2-38 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 38-1 70 110 210 NONE YES NONE YES YES 12.4 203  YES Example 38-2 70 115 210 NONE SOME NONE YES YES 11.6 130  YES Example 38-3 70 120 230 NONE NONE NONE NONE NONE 6.2 58 NONE Example 38-4 70 125 230 NONE NONE NONE NONE NONE 4.3 24 NONE Example 38-5 70 130 250 NONE NONE NONE NONE NONE 1.3 14 NONE Example 38-6 70 140 250 NONE NONE NONE NONE NONE 0.9 10 NONE Example 38-7 70 150 270 NONE NONE NONE NONE NONE 0.9 11 NONE Example 38-8 70 160 270 NONE NONE SOME NONE NONE 1.0 10 SOME Example 38-9 70 165 300 NONE NONE SOME NONE NONE 0.9 10 SOME

 

TABLE 2-39 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 39-1 70 110 210 NONE YES NONE YES YES 12.8 195  YES Example 39-2 70 115 210 NONE YES SOME YES YES 11.4 138  YES Example 39-3 70 120 230 NONE NONE SOME NONE NONE 6.8 64 SOME Example 39-4 70 125 230 NONE NONE YES NONE NONE 4.6 28 YES Example 39-5 70 130 250 NONE NONE YES NONE NONE 1.2 14 YES Example 39-6 70 140 250 NONE NONE YES NONE NONE 0.8 10 YES Example 39-7 70 150 270 NONE NONE YES NONE NONE 0.7  9 YES Example 39-8 70 160 270 NONE NONE YES NONE NONE 0.8  9 YES Example 39-9 70 165 300 NONE NONE SOME NONE NONE 0.8 10 SOME

 

TABLE 2-40 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 40-1 70 110 210 NONE YES NONE YES YES 12.6 201  YES Example 40-2 70 115 210 NONE SOME NONE YES SOME 11.9 124  YES Example 40-3 70 120 230 NONE NONE NONE NONE NONE 9.7 68 NONE Example 40-4 70 125 230 NONE NONE NONE NONE NONE 9.6 38 NONE Example 40-5 70 130 250 NONE NONE NONE NONE NONE 9.4 27 NONE Example 40-6 70 140 250 NONE NONE NONE NONE NONE 9.0 25 NONE Example 40-7 70 150 270 NONE NONE NONE NONE NONE 8.9 24 NONE Example 40-8 70 160 270 NONE NONE NONE NONE NONE 9.0 24 NONE Example 40-9 70 165 300 NONE NONE NONE NONE NONE 9.0 25 NONE

 

TABLE 2-41 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 41-1 70 110 210 NONE YES NONE YES YES 12.3 204 YES Example 41-2 70 115 210 NONE YES NONE YES SOME 11.3 134 YES Example 41-3 70 120 230 NONE SOME NONE NONE NONE 11.4 64 YES Example 41-4 70 125 230 NONE SOME NONE NONE NONE 10.9 39 SOME Example 41-5 70 130 250 NONE SOME NONE NONE NONE 10.2 28 SOME Example 41-6 70 140 250 NONE SOME NONE NONE NONE 10.2 25 SOME Example 41-7 70 150 270 NONE NONE NONE NONE NONE 10.0 25 SOME Example 41-8 70 160 270 NONE NONE NONE NONE NONE 10.1 25 SOME Example 41-9 70 165 300 NONE NONE NONE NONE NONE 10.1 25 SOME

 

It can be seen from Tables 2-36-Tables 2-41 that the molding time rises to 300 seconds if the cavity surface temperature Y° C. reaches 165° C. while the parison adheres to the cavity.

It can be seen from Tables 2-36-Tables 2-41 that the surface roughness Rt of the minute concavities/convexities of cavity needs to be 0.9 to 9.0 μm.

Samples in Table 2-39 have extremely poor paint film appearance. Also, samples in Table 2-40 have poor paint film appearance. Based on these results, it can be seen that the surface roughness Rt of the minute concavities/convexities of cavity needs to be 0.9 to 9.0 μm.

TABLE 2-42 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 42-1 70 110 210 NONE YES NONE YES YES 12.8 198 YES Example 42-2 70 115 210 NONE YES NONE YES YES 12.0 148 YES Example 42-3 70 120 230 NONE SOME SOME NONE NONE 7.0 59 SOME Example 42-4 70 125 230 NONE NONE SOME NONE NONE 5.1 28 SOME Example 42-5 70 130 250 NONE SOME YES NONE NONE 3.1 12 YES Example 42-6 70 140 250 NONE SOME YES NONE NONE 2.1 9 YES Example 42-7 70 150 270 NONE NONE YES NONE NONE 2.0 9 YES Example 42-8 70 160 270 NONE NONE YES NONE NONE 2.0 8 YES Example 42-9 70 165 300 NONE NONE YES NONE NONE 2.0 8 YES

 

TABLE 2-43 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 43-1 70 110 210 NONE YES NONE YES YES 13.3 208 YES Example 43-2 70 115 210 NONE SOME NONE YES YES 13.0 158 YES Example 43-3 70 120 230 NONE NONE NONE NONE NONE 8.0 69 NONE Example 43-4 70 125 230 NONE NONE NONE NONE NONE 6.1 38 NONE Example 43-5 70 130 250 NONE NONE NONE NONE NONE 4.1 22 NONE Example 43-6 70 140 250 NONE NONE NONE NONE NONE 3.1 12 NONE Example 43-7 70 150 270 NONE NONE NONE NONE NONE 3.1 11 NONE Example 43-8 70 160 270 NONE NONE NONE NONE NONE 3.1 11 NONE Example 43-9 70 165 300 NONE NONE NONE NONE NONE 3.1 12 NONE

 

TABLE 2-44 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 44-1 70 110 210 NONE YES NONE YES YES 12.4 199 YES Example 44-2 70 115 210 NONE YES NONE YES YES 11.8 155 YES Example 44-3 70 120 230 NONE SOME NONE NONE NONE 6.4 148 SOME Example 44-4 70 125 230 NONE NONE NONE NONE NONE 5.7 150 SOME Example 44-5 70 130 250 NONE NONE NONE NONE NONE 5.2 150 NONE Example 44-6 70 140 250 NONE NONE NONE NONE NONE 5.0 148 NONE Example 44-7 70 150 270 NONE NONE NONE NONE NONE 5.0 149 SOME Example 44-8 70 160 270 NONE NONE NONE NONE NONE 5.0 148 SOME Example 44-9 70 165 300 NONE NONE NONE NONE NONE 5.0 148 SOME

 

TABLE 2-45 Temper- Evaluation ature Molding Appearance of Cavity Time Surface Air Die of Example Z Y Second Deformation Condition Mark Line Bit Rt Sm Paint Film Example 45-1 70 110 210 NONE YES NONE YES YES 11.9 210 YES Example 45-2 70 115 210 NONE YES NONE YES YES 11.8 184 YES Example 45-3 70 120 230 NONE SOME NONE NONE NONE 6.2 165 SOME Example 45-4 70 125 230 NONE SOME NONE NONE NONE 5.4 162 SOME Example 45-5 70 130 250 NONE NONE NONE NONE NONE 5.2 164 SOME Example 45-6 70 140 250 NONE NONE NONE NONE NONE 5.1 162 SOME Example 45-7 70 150 270 NONE NONE NONE NONE NONE 5.1 162 YES Example 45-8 70 160 270 NONE NONE NONE NONE NONE 5.1 161 YES Example 45-9 70 165 300 NONE NONE NONE NONE NONE 5.0 159 YES

 

It can be seen from Tables 2-42-Tables 2-45 that the average peak-to-peak distance Sm of the minute concavities/convexities of cavity needs to be 10 to 150 μm.

Samples in Table 2-42 have extremely poor paint film appearance. Also, samples in Table 2-45 have poor paint film appearance. Based on these results, it can be seen that the average peak-to-peak distance Sm of the minute concavities/convexities of cavity needs to be 10 to 150 μm.

It can be seen from Tables 2-34-Tables 2-45 that the molded article for automotive exterior panel needs to have surface irregularities comprising a surface roughness Rt of 0.9 to 9.0 μm and an average peak-to-peak distance Sm of 10 to 150 μm.

The objects and advantages of the present invention may be further realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive. 

What is claimed is:
 1. An automotive exterior panel with a smooth surface comprising: a blow molded article of a noncrystalline resin exhibiting a tensile modulus of 2000 Kg/cm² or more at 75° C., wherein said blow molded article has surface irregularities comprising a surface roughness in the range of from 0.9 to 9.0 μm and an average peak-to-peak distance in the range of from 10 to 150 μm, and wherein said panel has a 15 to 150 μm thick paint film.
 2. An automotive exterior panel according to claim 1, wherein said panel is produced by disposing a parison, which is composed of a noncrystalline resin exhibiting a tensile modulus of 2000 Kg/cm² or more at 75° C., between mold halves having minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm; closing said mold halves to from a cavity; adhering said parison to said mold halves by introducing thereinto a pressurized air to said cavity whose surface temperature is set to Y° C. which falls in a range of Y=(0.96X+3) to Y=(0.96X+40), where X is a temperature at which the tensile modulus of the noncrystalline resin is 2000 Kg/cm²; opening said mold halves and removing said hollow molded article; and painting an external face of said hollow molded article with a 15 to 150 μm thick paint film.
 3. An automotive exterior panel with a smooth appearance, comprising: a blow molded article of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C., wherein said blow molded article has surface irregularities comprising a surface roughness in the range of from 0.9 to 9.0 μm and an average peak-to-peak distance in the range of from 10 to 150 μm, and wherein said panel has a 15 to 150 μm thick paint film.
 4. An automotive exterior panel according to claim 3, wherein said panel is produced by disposing a parison, which is composed of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C., between mold halves having minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm; closing said mold halves to form a cavity; adhering said parison to said mold halves by introducing a pressurized air to said cavity whose surface temperature is raised during the adhesion to y° C. which falls in the range of A<y<1.07B, where A is a peak crystallization temperature (° C.) in a DSC curve of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.; and B is a peak fusion temperature (° C.) in a DSC curve of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.; opening said mold halves and removing said hollow molded article; and painting an external face of said hollow molded article with a 15 to 150 μm thick paint film.
 5. An automotive exterior panel according to claim 3, wherein said panel is produced by disposing a parison, which is composed of a crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C., between mold halves having minute concavities/convexities such that the surface roughness is in the range of from 0.9 to 9.0 μm and the average peak-to-peak distance is in the range of from 10 to 150 μm; raising a cavity surface temperature so as to reach a temperature y° C. falling in the range A<y<1.07B, where A is a peak crystallization temperature (° C.) in a DSC curve of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C. while B is a peak fusion temperature (° C.) in a DSC curve of the crystalline resin which exhibits a flexural modulus of 9000 Kg/cm² or more at 23° C.; closing said mold halves to form a cavity; adhering said parison to said mold halves by introducing a pressurized air into the cavity; opening said mold halves and removing said hollow molded article; and painting an external face of said hollow molded article with a 15 to 150 μm thick paint film.
 6. An automotive exterior panel according to claim 3, wherein said crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C. is incorporated with 3% to 35% by weight of an inorganic filler.
 7. An automotive exterior panel according to claim 3, wherein said crystalline resin exhibiting a flexural modulus of 9000 Kg/cm² or more at 23° C. is polypropylene.
 8. An automotive exterior panel according to claim 1 wherein said non-crystalline resin comprises one or more non-crystalline resins chosen from the group of resins consisting of Polycarbonate (PC), Polystyrene (PS), styrene acrylonitrile (SAN), polyvinyl-chloride (PVC), noncrystalline polyamide, polysulfone, modified polyphenylene oxide (PPO), and a mixture of acrylonitrile, butadiene, and styrene (ABS). 